Numerical calculations of fast dynamos in smooth velocity fields with realistic diffusion

Galloway, D. J.; Proctor, M. R. E.

doi:10.1038/356691a0

Cited by 201 publications

(158 citation statements)

References 14 publications

Supporting

Mentioning

153

Contrasting

Order By: Relevance

“…is a periodic function of x and y with period X mx and Y mx , say (Roberts 1972;Galloway & Proctor 1992). This last step is not conceptually necessary though it affords an enormous computational saving.…”

Section: Formulationmentioning

confidence: 99%

On the Generation of Organized Magnetic Fields

Tobias

Cattaneo

Brummell

2011

ApJ

View full text Add to dashboard Cite

Motivated by the problem of the origin of astrophysical magnetic fields, we introduce two concepts. The first is that of a "system-scale dynamo", i.e., a dynamo that can organize magnetic fields on the scale of the astrophysical object. The second is that of an "essentially nonlinear dynamo". This is a dynamo which relies on a velocity driven by magnetic forces and/or magnetic instabilities. We construct a simple framework that can be used to study such dynamos and give examples in which the evolution is such to generate a system-scale field. We argue that this framework provides a valuable complementary approach to the more conventional studies based on kinematic mean-field dynamo theory.

show abstract

Section: Formulationmentioning

confidence: 99%

On the Generation of Organized Magnetic Fields

Tobias

Cattaneo

Brummell

2011

ApJ

View full text Add to dashboard Cite

show abstract

“…After all, many interesting flows do not possess stagnation points (such e.g. the flow, see [14] and turbulent flows in general), and in any case a stagnation point may be removed by a simple translation of the coordinate system. Rather it is the stretching ability of the flow that is relevant for the dynamo action.…”

Section: Topologymentioning

confidence: 99%

On the Structure of the Magnetic Field in a Kinematic ABC Flow Dynamo

Dorch

2000

Phys. Scr.

View full text Add to dashboard Cite

The kinematic induction equation of MHD is solved numerically using a staggered mesh in the case of the normal '111' ABC flow. Basic integral properties such as the growth rate of magnetic energy agree with previous findings, but careful 3D visualizations of the topology of the magnetic field reveal, however, that the conclusions about the modes of operation of this kinematic dynamo must be revised. The two known windows of dynamo action at low and high magnetic Reynolds number, correspond to two distinct modes, both relying on the replenishing of the magnetic field near the β type stagnation points in the flow. The results support the case for the normal ABC flow as a fast dynamo.

show abstract

“…While significant progress has been achieved in the case of moderate values of the magnetic Reynolds number [1,2], the fast dynamo limit has been tackled yet only with a few analytic flows [3,4], still remote from realistic configurations. Criteria to assess dynamo action (other than direct integration) are still missing.…”

mentioning

confidence: 99%

Time scales separation for dynamo action

Dormy¹,

Gérard-Varet²

2008

Europhys. Lett.

View full text Add to dashboard Cite

Abstract. -The study of dynamo action in astrophysical objects classically involves two timescales: the slow diffusive one and the fast advective one. We investigate the possibility of field amplification on an intermediate timescale associated with time dependent modulations of the flow. We consider a simple steady configuration for which dynamo action is not realised. We study the effect of time dependent perturbations of the flow. We show that some vanishing low frequency perturbations can yield exponential growth of the magnetic field on the typical time scale of oscillation. The dynamo mechanism relies here on a parametric instability associated with transient amplification by shear flows. Consequences on natural dynamos are discussed.

show abstract

Numerical calculations of fast dynamos in smooth velocity fields with realistic diffusion

Cited by 201 publications

References 14 publications

On the Generation of Organized Magnetic Fields

On the Generation of Organized Magnetic Fields

On the Structure of the Magnetic Field in a Kinematic ABC Flow Dynamo

Time scales separation for dynamo action

Contact Info

Product

Resources

About